Cryovolcanoes

Cryovolcanoes - I know how they form after their eruption and how, as they evolve, they can flatten and eventually disappear. What I cannot find is what sets off the eruption in the first place. Can someone please explain what sets off the eruption? How can water erupt? Methane, yes. Water? Is it the same as what sets off Yellowstone's geyser? Thank you.

Re: Cryovolcanoes

Tidal friction is a common theory for cryovolcanoes on moons like Triton or Titan or Enceladus. Subsurface heat may be sufficiently generated by the tidal stresses from the gas giant they are orbiting. With a little heat you might get a methane eruption. With more heat, maybe water or even water vapor. So, not like Yellowstone, which results from the internal heat of the Earth generated by radioactive decay. However, if there are cryovolcanoes on Pluto, which is not subject to tidal stresses, that could be from something else like radioactive decay or some other residual heat below the surface. Viv, if you need more, I would look up "tidal friction" on a search engine.

Re: Cryovolcanoes

If you have no trouble with the idea of basaltic magma erupting in Hawaii, you should have no trouble with ice erupting on large moons. Basalt and ice are both rocks. Once you accept that, all else follows naturally.

Re: Cryovolcanoes

Eclogite » February 6th, 2017, 4:10 pm wrote:If you have no trouble with the idea of basaltic magma erupting in Hawaii, you should have no trouble with ice erupting on large moons. Basalt and ice are both rocks. Once you accept that, all else follows naturally.

I'll go read it again but, if I understand right, it isn't ice that is erupting. It is water that erupts and then freezes into the volcanic shape. The freezing is caused by excessive cold of the surrounding (may I say "atmosphere"?).

What word do you use for what surrounds a planet or moon that has no atmosphere? Anyway, that's where the freezing comes from if I read right.

And that is why I also asked if it erupted for the same reason Yellowstone does - the fact that it's water erupting. The answer is 'no', I'm told.

Edit: I have apparently already given away the magazine but did find this at Wiki:

That is correct. But it isn't basalt rock that erupted from Mauna Kea in Hawaii, it was basalt magma. The basalt magma (lava) then "froze into the volcanic shape" on account of the freezing temperatures in Hawaii.

Obviously the temperatures that will freeze lava are higher than those required to freeze water. And we don't generally call it freezing, but - from a physical perspective - it is freezing.

One difference between most lavas and water is that water is mono-mineralic. That is it is made up of only a single type of crystal, whereas most lavas have several mineral types present. However, in the outer moons and planets, the word ice is deceptive. The ices may predominantly be water, but there is a substantial amount of methane, ammonia and other minor constituents present.

[quote="[url=http://www.sciencechatforum.com/viewtopic.php?p=315911#p315911]What word do you use for what surrounds a planet or moon that has no atmosphere? Anyway, that's where the freezing comes from if I read right.[/quote]I can't think of an applicable word, but I would refer to "the ambient surface temperature".

[quote="[url=http://www.sciencechatforum.com/viewtopic.php?p=315911#p315911]And that is why I also asked if it erupted for the same reason Yellowstone does - the fact that it's water erupting. The answer is 'no', I'm told..[/quote]It is a different mechanism, but both are driven by heat. In Yellowstone the temperature profile, driven by an underlying magma chamber, heat up the surrounding rocks sufficiently to generate steam from the water contained in the pore spaces of the rocks.

In the case of the cryovolcanoes the "surrounding rocks" are the ice that is melted by the available heat. This heat would arise from one of several sources: residual heat of satellite formation, radioactive decay, phase changes, tidal stresses, bolide impact. (I think I may have missed one.)

Re: Cryovolcanoes

Thank you, Eclogite. Sometimes using broader definitions for simple words (freezing) can enlighten. I am now wondering about something. Are you saying that the water came from ice rocks which were on the surface? These ice rocks are heated and melted by one of the possible causes. As the cause continues to heat, the then water is forced up into a plume. The plumes then re-freeze as surrounding temperatures hit them. The result is the form of a volcano. Then, as they start to melt at the top and flow down to the surface, they could perhaps re-freeze into ice rocks? Then it's the heat (or one of the other causes) that first melts the ice rocks and then forces the plumes. Right?

I have only omitted what starts the re-melting at the top of the volcano. I am sure I read that. I'll find it. But, do I have it right now?

Edit: Plus another source of the melting (quote from Wiki): In September 2016, NASA JPL and NASA Goddard scientists released findings that large Ahuna Dome on Ceres is a "volcanic dome unlike any seen elsewhere in the solar system. [The large] mountain is likely volcanic in nature. Specifically, it would be a cryovolcano -- a volcano that erupts a liquid made of volatiles such as water, instead of silicates. ... the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past."[13] In addition, at least some of Ceres' well known bright spots (notably including the ones in Occator crater) are likely also cryovolcanic in origin.[14]